And when those mice got valproic acid early enough, their memories didn't suffer as much as other at-risk mice that didn't get valproic acid.

The researchers -- who included Hong Qing, MD, PhD, of Canada's University of British Columbia in Vancouver -- didn't test valproic acid in people, but they speculate that valproic acid "might show significant improvements in early or mild Alzheimer's disease patients," but not in late or severe cases.

Qing's team notes that other researchers have tested valproic acid in Alzheimer's patients, but only to see if it's tolerable (it is) and if it curbed agitation and aggression (it didn't), not to see how it affects brain plaque or mental skills.

The study appears in today's edition of The Journal of Experimental Medicine.